I took my Vanishing Point FP with me on a business trip and didn't have any problems with it at all. I filled the converter before I left and did two ups and two downs and never had a leaking problem. I put the pen in a zip lock just in case though.
Did you do any in-flight writing? I usually do, I just carry it on in my shirt pocket. I've never had a problem, as a matter of fact I never understand what all the fuss is about.